#include <iostream>
#include <algorithm>
using namespace std;

const int N = 100010;
int n;
int q[N],tmp[N];

int merge_sort(int q[],int l,int r)
{
	if(l>=r) return 0;
	int mid = l + r >> 1;
	int res = merge_sort(q,l,mid) + merge_sort(q,mid+1,r);
	
	int i = l ,j = mid + 1;
	int k = 0;
	while(i<=mid && j <= r)
	{
		if(q[i]<=q[j]) tmp[k++] = q[i++];
		else
		{
			tmp[k++] = q[j++];
			res += mid - i + 1;
		}
	}
	for(int i = l,j = 0;i <= r;j++,i++) q[i] = tmp[j];
	return res;
}

int main()
{
	scanf("%d",&n);
	for(int i = 0; i < n; i ++ ) scanf("%d",&q[i]);
	
	int res = merge_sort(q,0,n-1);
	printf("%d",res);
	return 0;
 } 
